\begin{Verbatim}[commandchars=\\\{\},codes={\catcode`\$=3\catcode`\^=7\catcode`\_=8\relax}]
for each tuple t\PYGZus{}r in r do:
    for each tuple t\PYGZus{}s in s do:
        if t\PYGZus{}r and t\PYGZus{} satisfy join condition:
            add(t\PYGZus{}r, t\PYGZus{}s) to result
    end
end
\end{Verbatim}